Method and machine for metalworking



4 Sheets-Sheet l w m w m f a w m 0? 0 m 1 w p 2 fl a w w L. l. YEOMANS METHOD AND MACHINE FOR METALWORKING Filed April 29, 1940 Nov. 30, 1943.

Nov. 30, 1943. 1. YEOMANS METHOD AND MACHINE FOR METALWORKING Filed April .29, 1940 4 Sheets-Sheet 2 Nov. 30, 1943. 1 YEOMANS METHOD AND MACHINE FOR METALWORKING Filed April 29, 1940 4 SheetsSheet 3 ll'llll' Nov. 30, 1943. L. YEOMANS METHOD AND MACHINE FOR METALWORKING Filed April 29, 1940 4 Sheets-Sheet 4 fizveza or ZuczeizZYeo/nams 2 21 mm, @044 W jaw/29s.

Patented Nov. 30, 1943 UNITED STATES PATENT OFFICE METHQD AND MACHINE FOR IVIETAL- I WORKING Lucien LYeomans, Chicago, Ill., assignor of onehalf to George F. Bryant, Chicago, Ill.

Application April 29, 1940, Serial No. 332,149

21 Claims.

The invention relates to improvements in methods and machines for metal working and more especially for trimming the end edges of hollow metal articles such, for example, as forged cup shaped blanks for artillery shells.

The manufacture of artillery shells constitutes an excellent example of the utility of the present invention and, consequently, the invention has been described as applied to'such manufacture although it will be understood by those skilled in the art that the invention is also applicable to the trimming of a large variety of other forms of metal blanks. In the manufacture of artillery shells it is customary, first, to forge a cup shaped metal blank. Before finishing the interior and exterior of the blank, by suitable boring and turning operations, it is necessary to trim the blank for length since its side walls, formed as they are by a forging plunger thrust into a billet of metal to draw it to cup shape, may vary considerably in length for successive blanks. Heretofore, this trimming has been done on a lathe with a parting tool or by some similar comparatively slow process. In speedingthe production it is, of course, essential to eliminate all such slow operations or bottle necks in the production line. l

Accordingly, one object of thepresent inven tion is to provide a novel method and machine for speedily and effectually trimming-to length hollow metal articles such, for example, as forged artillery shell blanks. V More specifically, it is an object to provide a novel method and apparatus for trimming the edge of a hollow metal article by nibbling off the edge in successive bites circumferentially about the same. V 7

Another object is to provide a novel method and apparatus for edge trimming hollow metal articles, of such character that the article may be rigidly and easily clamped exteriorly against a shearing die and .a second cooperating shearing die or punch inserted 'intoftheinterior ofthe article and actuated to shear off in successive bites the edge of the clamped article.

Another object is to provide an improved method and apparatus of the character set forth in the preceding paragraphsand in which accurate gauging of the finished length of the blank is accomplished as an incident. to the trimming operation.

Still another object is to provide a machine of the type set forth embodying a novel arrangement for gauging the rotation of the blank required between successive shearing operations as the edge of the blank is being trimmed.

A further object is to provide such a machine embodying an improved form of cooperating clamping and shearing mechanism such as to insure firm clamping during each successive shearing operation together with release of the blank between successive cuts to permit repositioning of the blank- The invention also resides in the novel loading and supporting mechanism cooperating with the edge trimming dies.

Further objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings in which:

Figure l is a side elevation of a machine embodying the invention and adapted to carry out the novel method herein disclosed.

Fig. 2 is a fragmentary enlarged sectional view taken substantially along the line 2-2 in Fig. 5 and showing the mating portions of the die elements of th machine with a portion of the work piece between them.

Fig. 3 is an enlarged detail sectional view taken substantially along the line v(3-3 in Fig. '2.

I Fig. 4 is an enlarged. transverse sectional view taken substantially along the line 44 in Fig. 6

Fig. 5 is an enlarged front elevation of the central portion of the machine.

Fig. 6 is an enlargedside elevation, partially in section, of the central portion of the machine.

Fig. 6 is a detail longitudinal sectional view of the eccentrically mounted loading roller.

Fig. 7 is an exploded detail perspective View of the die elements.

Fig. 8 is a transverse sectional view taken substantially along the line 88 in Fig. 6.

Fig. 9 is a horizontal section taken substantially along the line 9-4 in Fig. 6.

Fig. 10 is a detail perspective View of a Work piece blank of a form adapted to be trimmedin the machine shown.

Fig. 10 is a perspective view of the trimmed blank. I

While the invention is susceptible of various modifications and alternative constructions, I

have shown in the drawings and will herein "describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims. V

dash line at T in Fig. it) to produce the smooth edged blank of Fig. 10 with its interior cavity of predetermined depth D.

Generally stated, my method comprises trim-. Ining the blank by nibbling off the blank edge in successive bites circumferentially about the same. More particularly, the blank is, in the present instance, clamped exteriorly against a stationary saddle shaped shearing die it (Fig. 7) and a cooperating shearing die or punch 22 is inserted in the open end of the blank (see also Fig. 6). Thereupo-n the punch I2 is moved toward the die H to shear off the incremental edge portion of the blank received between them. Then the blank is unclamped and rotated a short distance to bring the next increment of its edge between the active portions of the dies and the punch l2 again actuated to shear off another piece of the blanks edge. This operation is repeated until the whole edge of the blank has beentrimmed.

Several important advantages accrue from such a procedure in which the blank is, so to speak, trimmed from the inside out, that is by a shearing punch inserted into the open end of the blank and actuated in a direction radially oi the same.

For one thing, this makes possible firm though it simple clamping of the blank from its exterior. Further, it makes possible easy and accurate gauging oi the distance between the punch and the bottom of the cavity in the blank so that such cavity will be of preselected depth upon completion of the trimming.

. Turning now to the illustrative embodiment of the machine, which is particularly adapted to carry out the above described method, it will be observed in Fig. 1 that the machine resemblesin general outline a conventional punch press. On its bed i3 is rockably mounted a heavy'cast frame i l, pivoted at it and releasably held in adjusted position by a locking mechanism (not The frame Hi shown) actuated by a lever it. comprises an upstanding column ll having vertical guides l8 (see Fig. 5) on its front face and along which is vertically reciprocable a power actuated device in the form or" a ram is, which I is driven by a suitable power actuating mechanism (not shown in detail) of the well known form commonly used in punch presses for reciprocating the punch ram. Rigid with the lower portion of the frame M is a horizontal platform 26 on which is bolted a generally rectangular bed plate 2|.

In brief, the blank lii is clamped against the stationary die H, which is fast on the bed plate 2|, and the cooperating punch l2, having been inserted in the end of the blank, is reciprocated by the ram l9 to trim the blank, the latter being rotated incrementally about its axis between successive reciprocations oi the punch.

As a means of clamping the blank In in position, cooperating clamping jaws are carried, respectively, by the bed plate 2| and the ram l9. First as to the stationary clamping elements on the bed plate, two spaced pedestals 22 and 23 are bolted to this bed plate 2| (Fig. 6). On the top ill of the pedestal 23, the stationary die H is fixed in position by screws 24 passing through holes 24 in the side wings of the die (Fig. '7). On the top of the other pedestal 22 is screwed a saddle shaped wear plate 25 alined longitudinally with the similarly shaped top face of the die The central and inner end portions of the blank ID are thus received on the rigid saddle shaped members 25 and H, the latter element thus constituting a clamping jaw as well as a die.

To press the blank I!) down against the rigid jaws H and 25, a complemental jaw 26 presenting a bottom face of inverted saddle form (see Figs. 5 and 6) is utilized. The jaw 23 is carried by headed studs 21 threaded in the jaw and loosely slidable in holes 28 in a head 29, the heads on the studs 21 limiting the downward motion of the jaw 26 with respect to the head 29. A projection 33, integral with the lower side of the head 29 projects into a complemental cavity in the upper side of the jaw casting 26 so as to aid in guiding the latters vertical motion with respect to the head. Helical compression springs 3|, encircling the respective studs 21, are arranged with their lower ends bearing against the bottom of the cavity in the top of the jaw 26 and with their upper ends bearing against the bottoms of registering recesses formed in the projection 3|]. The jaw 26 is thus yieldably biased downward away from the head 29. The latter is fixed to the ram |9 (see Fig. 5) by a stud 32 received in a cavity 33 in the lower end of the ram and secured in place by dog screws 34. Thus, as the ram I9, and attached head 29, are reciprocatcd downward the clamping jaw 26 engages the top of the blank 10 and forces the latter downward against the lower rigid clamping jaws II, 25. The length of the studs 21 is so chosen with respect to the throw of the ram, however, that the jaw 26 will never go solid against the head 29 but will always be yieldably pressed against the work. Vertical rods 35, fixed to the head 29, pass through registering holes in the bed plate 2| and guide the head 29 in its vertical reciprocation.

It will be observed that with the clamping mechanism described above, as the ram I9 is reciprocated, the blank I0 is rigidly clamped in position as the ram approaches the end of its downward stroke but is released on each upstroke of the ram. ConsequentlY theblank l9 may be revolved about its longitudinal axis when the ram'lil is in its retracted or upper position so that the blank can be thus repositioned for the removal of asucceeding incremental portion of its edge upon the next downward stroke of the ram supported punch l2. It is contemplated, in the present machine, that the blank It shall be rotated by hand for this repositioning and since the blank may be quite heavy in the case of large shells, means is desirably provided for facilitating such rotation. For this purposetwo pairs of rollers 36 and 31 are arranged to bear against the lower side of the blank (Figs. 1, 5 and ,6). These rollers are carried respectively by yokes 38 and 39 extending beneath the blank and the rolls are journaled for rotation about axes longitudinal of the blank. The yokes 38, 39 are in turn mounted for limited vertical sliding motion on pedestals 40, 4!, respectively, being yieldably urged upward by compression springs 52. These compression springs encircle vertically slidable studs 43 threaded in the lower sides of the yokes 38, 39, and at their opposite ends bear respectively against the bottoms of the yokes and the bottoms of cavities in pedestals 40, 4| through which the studs pass. The length of free vertical travel for the roller-supporting yokes 38, 39 is such that the yokes will not seat solidly against their underlying pedestals 40, 4| until the rolls 36, 31 are depressed well below the faces of the clamping jaw members H and 25. By virtue of the arrangement described, when the pressure of the movable clamping jaw 26 is released the springs 42 will urge the pairs of rollers 36, 31 upwardly so that the blank I is slightlylifted from the jaws I l, 25 and is freely rotatable about its axis on the rollers. Upon subsequent depression of the jaw 25, however, the rollers 36, 31 are depressed, the springs 42 being substantially weaker than the springs 3| so that the blank is pressed solidly down against the stationary jaws ll, 25 and the rollers 35, 31 merely pushed down out of the way.

As to the die mechanism itself, the active portion of the stationary die I l comprises a relieved edge 46 (Figs. '1, 8 and 9) defining a rectangular notch at the inner end of the die block. The cooperating movable die or punch 12 is of block form (Fig. '7) and its forward or nose portion is relieved to form a. front cutting edge 45 and side cutting edges 45 dimensioned to enter the complemental notch in the stationary die and shear off the portion of the blank Ill received between them (see also Figs. 2 and 4). The die or punch I2 is received in a complemental opening 41 (Fig. 6) in a vertically reciprocable plunger 48 fixed to the head 29. The usual tapered transverse locking pin 49 (see also Fig, holds the die [2 in position. A semi-circular integral projection 573 on the front of the plunger 48 embraces the top of the projecting end of the punch I2 and rigidly backs the same.

Provision is made for repositioning the die ll horizontally after it has been ground. For this purpose the holes 24 in it (Fig. 6) are somewhat ovaled so that it can be slid horizontally a limited amount without interference by the shanks of the screws 24. A transverse key II in mating keyways I l and l i formed in the opposed faces of the die block H and pedestal 23, holds the die block against horizontal movement and in a position of horizontal adjustment determined by shims inserted in the keyway li at the side of the key Il In order to gauge the requisite rotation of the blank In between successive cuts of the shearing dies, a stop pin 5! is utilized (Figs. 2, 3, 6 and 9). This pin 5| is splined for axial sliding movement in a bore 52 in the plunger 53 by a spline screw 53 having its inner end projecting into a keyway 54 in the side of the pin. A compression spring 55, interposed between the inner end of the pin and the bottom of the bore 52, yieldably urges the pin outward toward the blank ii). A projecting end of the pin 5! is reduced in cross section in the form of a thin nose 55 positioned to bear against the blank ill. Upon reference to Fig. 2 it will be seen that as the punch 12 descends it shears a bite from the edge of the blank. Then, when the ram 48 reascends the pin 5| is free to move outward so that its reduced nose 56 projects into the cut or notch in the blank (Fig. 4) Then the blank is revolved in a counterclockwise direction (as viewed in Fig. 4) so that the opposite, or left edge, of the notch in the blank is brought into abutment with the nose 55 on the stop pin 5|. The requisite degree of revolution for the work blank is thus accurately gauged by the stop pin for the successive bites to be taken by the shearing dies. These successive bites or cuts are indicated in dot-dash lines in Fig. 4.

The utilization of a shearing punch inserted into the open end of the hollow work piece as described also makes it possible to gauge the depth of the cavity, or, in other words, the trimmed length of the work piece side walls, in a simple and accurate manner.- For this purpose a gauge mechanism is inserted into the interior of the blank it! (see Fig. 6) comprising, in the present instance, a rod 51 being fixed to it two transverse sheet metal disks 58 and 59, dimensioned to be received loosely in the interior of the blank. On the inner end of the rod 51 is adjustably threaded a cap 65 with a lock nut 6|. The over-all length of the gauge can, of coursebe adjusted by threading the cap along the rod. When the gauge shown is inserted into theblank, the cap 60 bears against the bottom of the cavity in the blank while the outer face of the disk 58 is presented to the opposed face of the punch l2. The blank W, with the gauge in it, is pushed longitudinally into position on the machine until the punch 52 bears against the opposed face of the gauge 59, whereupon the punch is accurately positioned to trim the blank to a desired and fairly accurately determined length.

For the loading of heavy blanks in the machine an eccentrically mounted loading roller 62 is used (Figs. 6 and 6 This roller is of hourglass shape and is journaled for rotation on a shaft 53 having eccentric trunnions 64 projecting from its opposite ends. These trunnions are in turn journaled for oscillation in a pedestal 65. A handle 66 is fixed to one of the trunnions 5d. When the handle 63 is in the full-line position of Fig. 6 the roller 62 is displaced beneath the level of the jaw faces on elements 25 and H so that it does not interfere with the seating of the blank In on these elements. To raise the roller 62 into operative position, the handle 56 is swung to the dot-dash-line position of Fig. 6. The roller is thus elevated and in loading one of the blanks ID the latter is shoved endwise over the roller ilritolzoperative relation with the die elements In the operation of the machine described, the gauge device 515l is slipped into the cavity in a blank I!) (Fig. 6). The handle 65 is swung to raise the loading roller '52 as described, and the blank is pushed endwise over the roller until the gauge end disk 59 abuts against the punch l2. The-handle 65 is then swung back to its initial position so that the blank it drops down on the supporting elements 25, ll.

Having positioned the blank iii in the machine as described, the operator sets the drive mechamsm in operation by the usual control treadle or the like (not shown) thereby causing the ram l9 (Fig. 5) to descend. In this descent of the ram the yieldab-ly mounted clamping shoe 25 first engages the blank and presses it firmly against the opposed lower clamping jaws. Further descent of the ram drives the shearing punch I2 through the edge portion of the blank so that the punch and cooperating die I l bite a notch in the edge of the blank.

Upon the reascent of the ram 89, the punch I2 is withdrawn from the notch cut in the work piece and the clamp shoe 25 releases the work. The operator grasps the released work piece and turns it about its axis to present the next adjacent part of the edge to the punch for trimming. Such turning of the work piece takes place on the freely revoluble rollers 36, 31 which spring up to lift the Work slightly from the rigid seating elements ll, 25 as soon as the pressure of the upper clamp shoe 28 is released. The extent of work piece revolution, in the repositioning operation, is governed by the stop pin 5i Whose nose is projected into the notch cut in the work piece. As the work piece is turned by the operator, the nose 56 of the stop pin contacts the side of the notch thus locating the work piece for the next shearing operation. Having thus relocated the Work piece, the operator causes the ram I9 to descend again so that the work is clamped as before and another bite taken out of its edge by the punch. This operation is repeated about the entire periphery of the blank to complete the trimming. During all of this trimming the outer end of the gauge is kept pressed against the abutting outer end of the punch I2, thereby determining the depth of the cavity in the trimmed blank.

As the chips or pieces are punched from the end of the blank Ii] they drop down into a cavity 61 in the pedestal 23 (Figs. 8 and 9) through which they fall into a registering cavity 68 in the bed plate 2| (Fig. 6). From there they are free to emerge through a suitable channel (not shown) in the bed plate or platform. If desired the frame 14 (Fig. 1) can be tilted backward (to the right) about its pivots IE to aid the gravity flow of chips as Well as to make easier the endwise loading of the blanks.

I claim as my invention:

1. The method of trimming the edge of a hollow metal article, which comprises gripping the article exteriorly to press it laterally against a die, and shearing off the edge portion of the ar ticle in incremental steps in each of which an incremental piece of material is completely severed from the article by a cooperating shearing die punch located interiorly of the article.

2. The method of trimming the edge of the open end of a hollow metal article which comprises pressing the article laterally against one of a pair of reciprocable shearing dies with the other die projected into the interior of the article, reciprocating the die toward each other in a direction transverse to the wall of the article being 'sheared to bite out chunks of the article as the dies come together and rotating the article between reciprocations of the dies to present successive portions of the article edge to them.

3. The method of trimming the edge of a cup shaped metal article which comprises inserting a gauge in the interior of the article and supporting said gauge on the inner surfaces of the article in abutment with the bottom of the interior of the article, said gaug presenting an outer gauging surface spaced from the bottom of the interior of the article a preselected distance, and nibbling off the edge of the article with a shearing punch inserted into the open end of the article and contacting said gauge face.

4. The method of trimming the edge of a cup shaped article which comprises inserting a shearing punch into the open end of a cup shaped article and effecting relative movement of the punch in the direction laterally of the article to bite off completely from the article successive chunks of th articles edge circumferentially about the latter.

5. In an apparatus for trimming the edge of a hollow metal article, the combination of a pair of shearing dies including a stationary die. and a relatively movable die punch, means for exteriorly gripping the work piece and pressing the same against said stationary die with said punch projecting into the interior of the article, and means for reciprocating the inserted punch towardand away from said stationary die to shear ofi completely, successive incremented edge portions of the blank received between said dies.

6. A machine for trimming the end edge of a hollow cylindrical work piece comprising, in combination, means including a stationary shearing die forming a seat for a work piece of the type indicated, said die presenting a notchform opening bordered by shearing edges and underlying an end portion of the work piece on said seat, a plunger reciprocable in a path extending generally diametrically across the end of the seated work piece and at a point adjacent said die, a punch on said plunger projecting laterally from the plunger into the interior of the work piece and presenting shearing edges complemental to those of said die and facing toward the same in the direction of plunger travel, and a back-up abutment on said plunger bearing against the rear side of said punch opposite the cutting edges of the latter.

7. In a machine of the type set forth, the combination of a power actuated reciprocable member, a shearing punch rigid with and projecting laterally from said member, a cooperating stationary shearing die, and means for releasably clamping a hollow work piece against said stationary die with said punch projecting into the interior of the work piece.

8. In a machine of the type set forth, the combination of a power actuated reciprocable member, a shearing punch rigid with and projecting laterally from said member, a cooperating stationary shearing die, means for releasably clamping a generally tubular open-ended work piece against said stationary die with the axis of the work substantially normal to the path of reciprocation of said member and with the punch projecting into the open end of the work piece, and means for actuating said clamping means in timed relation to the reciprocation of the punch to set the clamp as the punch approaches the cooperating die in its active stroke and to release the work piece as the punch is withdrawn in the opposite direction, whereby the work piece is freed for repositioning after each active stroke of the punch to bring successive edge portions of the work into poistion to be sheared ofi by the punch.

9. In a machine of the type set forth, the combination of a pair of relatively reciprocable shearing die elements movable toward and away from each other to notch the edge of a generally tubular work piece inserted therebetween, means for releasably clamping the work piece in position with its edge portion inserted between the dies, and means for actuating said clamping means in timed relation with the movement of said dies to clamp the work as the dies are moving toward each other in their working stroke and to release the work as the dies move apart, whereby the work may be revolved intermediate successive working strokes in order to effect step-by-step notching of the work piece about its entire periphery.

10. In a machine of the type set forth, the combination of a reciprocable power actuated tool support, a shearing punch on said support and projecting laterally from it for insertion in the open end of a hollow work piece, a stationary clamping jaw, and a yieldably mounted.

second clamping jaw carried on said tool support in opposed relation to the first mentioned clamping jaw for engagement with the work in advance of its engagement by said punch during the working strokes of said reciprocable support.

11. In a machine of the type set forth, the combination of a pair of clamping jaws presenting generally arcuate opposed surfaces for the reception'of a cylindrical work piece therebetween, a power actuated ram reciprocable. in a path located at one end of the jaws and transverse to the am's of a cylindrical work piece between them, means for stationarily supporting one of said jaws, means for yieldably supporting the other jaw on said ram, a shearing punch, and means supporting said shearing punch on said ram in position to reciprocate in the adjacent open end of a hollow work piece received between said jaws to shear off the edge portion of the work in the course of the rams reciprocation.

12. In a machine of the type described, the combination of means for supporting a cylindrical hollow work piece, a power actuated member reciprocable with alternate working and return strokes in a path extending generally diametrically across one end of a work piece on the first mentioned means, a shearing punch projecting from said member toward the work piece to engage and notch the latters adjacent edge at substantially the end of said members working strokes, and an abutment on said member yieldably urged toward the work piece and positioned to enter, at the end of each return stroke of said member, the notch formed by the punch in the previous working stroke in order to constitute a locating abutment for stopping the work piece with a fresh edge portion of the latter in the path of the punch upon rotational repositioning of the work piece.

13. In a machine of the type described, the combination of means for supporting a cylindrical hollow work piece, a power actuated member reciprocable with alternate working and return strokes in a path extending generally diametrically across one end of a work piece on the first mentioned means, a shearing punch projecting from said member toward the work piece to engage and notch the latters adjacent edge at substantially the end of said members working strokes, a stop pin mounted on said member for limited endwise movement in a path paralleling the Work piece axis, means for yieldably urging said stop pin outward toward the work piece, and said pin having a thin outer end nose portion substantially alined with one side edge of the punch and positioned to enter, at the end of each return stroke of said member, the notch formed by the punch in the previous working stroke in order to constitute a locating abutment for stopping the work piece with a fresh edge portion of the latter in the path of the punch upon rotational repositioning of the work piece.

14. In a machine of the type described, the combination with means for supporting a hollow open-ended work piece, and power actuated means for notching an end edge of the work piece, of means for gauging the repositioning of the work piece to locate an unnotched portion in operative relation with said notching means after each actuation of the latter.

15. In a machine of the type set forth, the combination of a vertically reciprocable shearing punch, means forming a generally horizontal clamping seat for a tubular hollow work piece to support the same with the path of reciprocation of said punch extending across an end edge of the work piece, and means including yieldably mounted rollers engageable with the work piece at points spaced about its periphery for lifting the same from its seat and rollingly supporting it for axial rotation free of the seat to bring a fresh edge portion into operative relation with the punch.

16.. In a machine of the type set forth, the combination of a vertically reciprocable shearing punch, means forming a generally horizontal clamping seat for a tubular hollow work piece to: support the same with the path of reciprocation of said punch extending across an end edge of the work piece, means including yieldably mounted rollers engageable with the work piece at points spaced about its periphery for lifting the same from its seat and rollingly supporting it for axial rotation free of the seat to bring a fresh edge portion into operative relation with the punch, means including a cooperating upper clamping jaw for pressing the work piece down solidly against said seat and at the same time depressing said yieldably mounted rollers, and means for actuating said upper clamping jaw into and out of operative relation with the work in timed relation with the reciprocation of said punch. I

1'7. In a machine of the type set forth, the combination of a vertically reciprocable power actuated plunger, a shearing punch fixed to said plunger, upper and lower clamping jaws shaped to receive between them a generally tubular hollow work piece and disposed to support the latter with the path of reciprocation of said punch extending across an end edge of the work piece, means stationarily supporting the lower clamping jaw, a plurality of rollers disposed to contact the lower side of the work piece at points spaced about its periphery, means including a compression spring for yieldably urging said rollers upward to lift the work piece from said lower jaw and rollingly support it for axial rotation free of said lower jaw to bring a fresh edge portion of the work into operative relation with the punch, means for supporting said upper clamping jaw on said reciprocable plunger, and means including a second compression spring for urging said upper jaw downwardly with a force greater than that exerted by the first spring means on said rollers, whereby said upper jaw forces the work piece down solidly against the lower jaw and depresses said rollers upon descent of said plunger.

18. In a machine of the type set forth, the combination of a vertically reciprocable shearing punch, means including opposed upper and lower clamping jaws shaped to receive a tubular hollow work piece therebetween and support the same with the path of reciprocation of said punch extending across an end edge of the Work piece, a loading roller extending transversely of the axis of a work piece received between said jaws and at a point beneath a work piece resting on said lower jaw, and means including an eccentric support for said loading roller for lifting and lowering the same respectively above and below the surface of said lower aw.

19. A nibbling machine for trimming the end edge of a hollow cylindrical work piece comprising, in combination, means for stationarily supporting a hollow cylindrical work piece, a tool support reciprocable'in a, path extending gen erally diametrically across an open end of a work piece on said supporting means, and means including a punch fixed on said tool support in position to project laterally from the support into the open end of the work piece for biting off incremental edge portions of the work piece as the punch is reciprocated across the edge of the work piece by said tool support.

2(). The method of trimming to predetermined length a heavy cup shaped forged metal blank for an artillery shell preparatory to turning and boring the same, which comprises, locating a shearing tool within the open end of the blank, efiecting a relative movement between the tool and blank in a direction transverse to the blanks longitudinal axis to punch out a notch in the edge of the open end of the blank as the tool moves relative to the blank in a direction out- Ward away from said axis, and repeating said notching operation step-by-step circumferentially about the edge of the open end of the blank. 21. The method of trimming to predetermined length a heavy cup shaped forged metal blank for an artillery shell preparatory to turning and boring of the same, which comprises, shearing ofi incremental chunks of the edge portion of the blank, one after another in a series, about the edge of the open end of the blank.

LUCIEN I. YEOMANS. 

